New York (CNN) -- At least 13 people were killed when a tour bus overturned in the Bronx early Saturday, officials said.

The driver of the bus said he was cut off by a truck driver -- who continued driving -- causing the bus to swerve into a guardrail, flip on its side and smash into a pole that sliced through more than two thirds of the vehicle, according to New York City Police Commissioner Ray Kelly.

In addition to the dead, eight people among the 32 passengers on board suffered severe injuries, Kelly said. The victims were rushed to the St. Barnabas and Jacobi hospitals.

"We have no minor injuries at this time, everyone is considered serious," said Kelly, adding that the crash likely occurred at high speeds.

The accident occurred just after 5:35 a.m. as the bus was traveling south on the New England Thruway near the border of Westchester and the Bronx, Kelly said. It had departed from the Mohegan Sun Resort and Casino in Uncasville, Connecticut. When emergency teams arrived at the scene "we found several people walking around dazed," Kelly said, and at least seven passengers had to be extracted by removing seats and cutting a hole in the remaining roof.

Most of the passengers were thrust to the forward third of the bus as it split open upon hitting the pole, Kelly added.

Investigators say they have information on the license plate of a vehicle that may have been involved in the accident.

"Our -- and the entire city's -- prayers, thoughts and sympathies are with the victims, and their families and loved ones," Mayor Michael Bloomberg said in a written statement Saturday. "Many of the victims are Chinese, and we have brought in translators to help assist the families."

The National Transportation Safety Board said it has deployed a 16-member team to investigate the crash.